[TRAFODION-2569] Improve handling of index hintsAllowing hints in update and delete statements - they apply to thescan of the table. Also making sure that heuristics to eliminateindexes don't apply to indexes listed in a hint. Excluding the rightchild of an index join when giving priority to plans that satisfy thehint. Otherwise, an index join (index - base table) could be chosenwhen the hint lists the base table.Also removed some unused interfaces:- no_log option in grammar, since it made changing the update syntax harder. If we decide to implement incremental MVs in the future, we should use a better parser or a different syntax for the no log feature.- Some obsolete parser rules.- Another set of hints in the scan node, in addition to those in the RelExpr.